This article proposes that same-sex marriage bans channel individuals, particularly bisexuals, into heterosexual relationship and relationships, impermissibly burdening sexual liberty interests protected under Lawrence v. Texas. A claim from sexual liberty departs dramatically from the legal paradigms and advocacy strategies that currently dictate the terms of constitutional debate on this issue. This article proceeds in four parts. Part II develops the legal argument that same-sex marriage bans are unconstitutional under Lawrence because they substantially burden the right to choose homosexual relations and relationships. Part III posits bisexuality, understood as dual-sex desire, as an illuminating perspective on the coerced heterosexuality of marriage. Part IV asks why same-sex marriage advocates, far from advancing any argument specifically grounded in bisexuality, faithfully uphold what Professor Kenji Yoshino dubbed "an epistemic contract of bisexual erasure." Part V describes the "politics of containment" lurking behind the rhetoric of homosexual equality. The article concludes that a claim from (bi)sexual liberty is worth raising in same-sex marriage litigation despite the existence of sometimes-successful alternatives.